...and yet that was exactly the fate that she forced upon every last one of her people without their consent, so I daresay she met a fitting and rather poetic end after all was said and done.
The Ancients had a system in place where, when they felt the time was right, they would willingly give themselves to Etheirys. Hythlodaeus speaks of it at length during the Elpis story segments.
Venat, however, inflicted a non-consensual death upon every last Ancient (barring the three Unsundered) which involved identity death, loss of memories, separation from loved ones and all sorts of unpleasant factors such as a forcibly altered body, lower intelligence, less strength, a shorter lifespan and other elements.
As such, I think it's only fitting that Venat went out the way that she did - burning through the very candle of her life. As much as I think that her overall plan was flawed, the last burst of her energy helped get the player character and the Scions to Ultima Thule and the lingering remnants of the Mothercrystal served to bestow Zenos with the ability to follow in their footsteps.
I'm not saying it isn't a bleak end for her because it very much is, though Endwalker was very much pushed as the conclusion of the Hydaelyn and Zodiark arc and such a conclusion seems fitting to me.
I know what you're referring to when you mention lower intelligence but I'm not sure if it's true. Emet-Selch claims that the sundered are less intelligent than the unsundered, but I don't recall seeing any actual evidence of this. The people of the Source and people of the shards don't seem to be very different save for their aetheric density. I think it's possible that he could've come to this conclusion after seeing the sundered Ancients go from a utopia to warring with one another, but as we see in Elpis, while the society of the Ancients was for the most part peaceful, they weren't as perfect as Emet-Selch made them out to be.
That makes me wonder too is the mental capacity between say people on the 1st so different from the people on the source? That's a 1/14th vrs 8/14th comparison of two sundered species... meaning less for the lesser shard that is.
Intelligence is a difficult attribute to write in general, though I'm inclined to take it at face value even if it isn't obviously measurable at a glance. Let's not forget that the cleverest of the Sundered have an immense amount of studying to back them up and in some cases - such as with G'raha - they've been artificially infused with knowledge they would not otherwise possess.
Intelligence is always shown in the game especially by going by the literal definition of it
in·tel·li·gence
/inˈteləjəns/
noun
1.
the ability to acquire and apply knowledge and skills.
The normal people on the first demonstrated that just by figuring out that PC was the Warrior of Darkness...
Granted that was a simple deduction that they were able to process but then there's also people are able to figure things out like the cat guy on the first (the daedulus heir not kai shirr god not kai shirr looks good in the 2b outfit though..).. its why I wonder because say comparing him to Cid they both seem and could be considered to be on the same common ground
In a way it makes me sometimes wonder when he says that due to the fact that Emet already sees the sundered as lesser being than him. (And yes in some ways they are due to being sundered will not and am not arguing that also theodric not arguing with you just a nice discussion ^_^) So in a way it could be his prejudice speaking when he says that.
Well, when we talk about attributes of the Sundered in the present, they are different from the Sundered of the past.
12,000 years is a long amount of time, and there's no way to tell how that much time caused the Sundered to adapt to having bodies receptive to Dynamis. It may be that regardless of Shard or Source, the Sundered have been slowly snowballing towards a similar intellect due to these Dynamis induced adaptations.
Beyond that, we know for a fact that most Sundered do not know about the cycle of rebirth inherent in Etheirys's existence. They do not know precision aether manipulation, by and large. It wasn't just intellect lost, but also knowledge.